Automatic choke valve



2 shuts-sheet '1;

Filed Aug. 29.; 1932:

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Sept. 9g, 19412;,-` c. JQ swlGER-r AUTOMATIC CHOKI?.y VALVEy Fired Aug.. 29,. 1932- z`sneetssneet 2 Patented Sept. 9, 1947 AUTOMATIC CHOKE VALVE Clarence J. Swigert, Detroit, Mich., assignor, by

mesne assignments, to General Motors Corporation, Detroit, Mich., a corporation of Dela- Ware Application August 29, 1932, Serial No. 630,805

4 Claims. (Cl. 12S-119) To facilitate starting and to insure most efficient operation of an internal combustion engine under different conditions, there is commonly provided in the air intake passage of the carburetor of the engine a valve (commonly called the choke valve) which controls the'fiow of air through the passage and, consequently, the

ratio of fuel to air in the combustible mixture supplied by the carburetor to the cylinders of the engine. Many mechanisms, some of which regulated the position ofthe choke valve in accordance with the temperature of the engine and others of which regulated the position ofthe choke valve in accordance with the speed and load of the engine, have been suggested for automatically regulating the position of the choke valve of an internal combustion engine.v However, since, as my 'experiments have shown, the ratio of fuel to air which is desirable in the combustible mixture supplied to the cylinders of an internal combustion engine is a functionboth of the temperature and of the speed and load of the engine, none of these mechanisms has entirely satisfactorily accomplished the result that it was designed to accomplish.

This invention relates to mechanism for automatically regulating the position of the choke valve of the carburetor of. an internal combustion engine and resides principally in such a mechanism which is so constructed and/or arranged that the po'sition of the choke valve is aifected by both the temperature and the speed. and load of the engine.

For a 'better understanding of the nature and objects of the present invention, reference is made to the following specication in which there are described the preferred embodiments of my invention which are illustrated in the accompanying drawing.

In-the accompanying drawing:

Fig. 1 is a view of 'choke Valve regulating mech- I anism in which my invention is embodied installed on an internal combustion engine.

Fig. 2 is a top plan view of the mechanism shown in Fig. 1 with the cover removed.

Fig. 3 is ,a section taken on the line 3-3 o Fig. 2.

Fig. 4 is' a section taken on the line 4 4 of Fig. 3.

Fig. 5 is a view of a second form of choke valve regulating mechanism in which my invention is embodied installed on an internal combustion Fig. 6 is a section taken on the lines 6-6 of Figs. 5 and 7 but showing the parts in the positions which they occupy when the choke valve is fully open.

Fig. 6a is' an enlarged exploded perspective view of parts of the mechanism shown in Figs. 5 and 6.

Fig. 7 is a fragmentary view taken as indicated by the line 1-1 of Fig. 6 but showing the parts in the positions which they occupy when the choke valve is fully open.

Fig. 8 is a fragmentary section taken on the line 8-8 of Fig. 5.

Fig. 9 is a View of a third form of choke valve regulating mechanism in which my invention is embodied installed on an internal combustion engine.

In Figs. 1 to 4 of the drawing. there is shown part of the induction system ofan internal combustion engine which includes a carburetor I0 l into which air is drawn through the conduit II engine with the parts in the positions which v and from which combustible mixture is discharged through the conduit I2 and a manifold I3 through which the combustible mixture discharged from the .conduit I2 is conducted to the intake ports of the cylinders of the engine. Within the conduit- I2 on the shaftr I4, there is mounted a throttle valve 52 of the butterfly type, and within the conduit II on the shaft I5, there is mounted a choke valve I6 of the butterfly type which is notable only in this, that, as shown in the drawing, the portion thereof which moves inwardly as the valve opens is of greater -area than the portionl on the opposite side of the shaft I5 and,

consequently, that now of air into the carburetor will tend to open it.

In the form shown in Figures 1,to 4, the mechanism in which my invention is embodied includes a body I1 which consists of a pair of spaced parallel walls I8 and I9 mounted on and formed lintegrally with a base 20 which is seated on and secured by means of screws, such as 2|, to the intake manifold I3. The open sides of the body I'I are closedby a cove'r 22.

To the outer side of the wall I8, there is secured an element 23 on which there is provided a sleeve-like extension which projects through an opening' in the wall into the interior of th'ebody I1. In the element 23, there is journalled a hollow shaft 24 which projects into the interior ofthe body I1 beyond the mentioned extension of the element 23. Through the hollow shaft 24 and through the wall I9 of the body, there extends a shaft 25 which is journalled in the hollow shaft and in the wall I9. To the end of the shaft 25 which extends through the wall t9, there is xed, without the body I1, a 4crank arm 26 which is connected by a link 21 to an operating arm 28 which is Xed to the shaft on which the choke valve I6 is mounted. To the opposite end of the shaft 25, beyond the outer end of the hollow shaft 24, there is secured the inner end of a bimetallic thermo-sensitive coil spring 29 which is located within a cup-shaped housing 30 which is secured to the element 23 by the screws 3i which secure it to the wall I8. The outer end 4of. the thermo-sensitive element 29 is secured to the outer end of an arm 46 whose inner end is xed to the outer end of the hollow shaft, 24. In the walls I8 and I9 of the body, there are provided aligned openings through which extends and in which there is journalled a shaft 32 on '41 fails, it tends to rotate the shaft 25 in such a direction (clockwise, as viewed in Figure 1, or counter-clockwise, as viewed in Figure 4) as to move the choke valve toward closed position and to rotate the hollow shaft 24A in such a direction (clockwise, as viewed in Figure 4) as to move the piston toward the head end of the cylinder and (3) when its temperature falls below a, predetermined minimum (e, g., V'70 F. to 80r F.) it will, if unresisted, maintain the choke valve in fully closed position. From what has been said in the preceding sentence, it will be apparent that the thermo-sensitive element 29, when its temperature is below the mentioned predetermined minimum, tends to maintain the choke valve in fully closed position -and when'its temone ofwhose ends, without the body, there is xed a. crank arm 33 ,which is connected, through a link 34,' a bell crank 35 and a link 36, with an arm 31 which is xed to the shaft on which' the throttle valve 52 is mounted. l

On one end of the base 20 and integraltherewith, there is formed a hollow cylinder 38 whose outer end is closed by a head 39 and whose open inner end is located between the walls I8 and I9. The interior of the cylinder communicates with the interior of the intake manifold i3 through a passage 40 which extends through the `head 39, the base 28 and the upper wall of the intake manifold; Within the cylinder 38, there is Vlocated .a piston 4I which is urged away from the head end of the cylinder and toward the abutment which serves to limit its outward movement by` a coil spring 42 and whose outer end is connected by a link 43 to the arm 44 of a bracket 45 which is xed to the portion of the hollow s'haft 24 within the body.

On the shaft 32, within the body I1, there is mounted suiciently loosely as to be freely rotatable thereon a U-shaped elementr 41. One of the arms of the element 41 extends between the branches of a bifurcated arm 48 which is formed on the bracket 45 and overlies a pin 49 which extends therebetween; and the other of the arms of the element 41 is located between the arm 48 and the wall I9 of the body. Between the element 41 and the wall I9 of the body, there is xed to the shaft 32 a similar U-shaped element 50. To the shaft 25 between the inner end of the hollow shaft 24 land the lwall I9 of the body, there is xed an arm V5I whose extremity overlies the juxtaposed arms of the elements 41 and 50.

While, as indicated in Figure 3, the choke valve adjusting mechanism illustrated in Figures 1, 2, 3 and 4 of the drawing and hereinbefore described is designed to be installed on an engine with the thermo-sensitive element 29 located in such close juxtaposition to the exhaust manifold I I1 thereof that it will be aected by the heat radiated therefrom, it will be understood that, if so desired, the mechanism maybe so installed that the thermosensitive element will be affected by heat radiated perature equals or`exceeds the mentioned predetermined minimum, tends toregulate the position of the choke va1ve,in accordance with its temperature and, consequently, in accordance withthe temperature of the exhaust manifold It will, however, be noted that, when the engine on which the mechanism shown in Figures l, 2,

3 and 4 is installed is operating, two other forces,'

viz., the now of air through the conduit Il'and the pressure within the intake manifold may affect the position of the choke valve I6 and, consequently, that the position of the choke valve is a function of -both the temperature and the speed and load of the engine. It is obvious that an increase in the rate of ow of air through the conduit I I will tend to move the choke valve toward fully open position, through the shaft 25, coil up the thermo-sensitive element 29 and through it, the hollow shaft 24, the bracket 45 and the link 43 move the piston 4| toward the head end of the cylinder 38 and that a decrease in the rateof ow of air through the conduit I I will tend to uncoil the thermo-sensitive element 29 and permit the spring 42 to expand and move the piston awayfrom the head end of the cylinder and to permit the thermo-sensitive element and/or the spring 42 to move the choke valve toward fully closed position. It is also apparent that a decrease in the pressure within the intake manifold of the engine will tend to move the piston 4I toward the head end of the cylinder 38 and, through the link 43, the bracket 45, the hollow shaft 24 and the arm 46 uncoil .the thermo-sensitive elevment 29 and move the choke valve toward fully ment and move the choke valve toward fully -ciosed position.

from a part of the engine other than the exhaust manifold.

The thermo-sensitive element 2,9 is Aso con-` structed and' arranged that (l) as its temperature rises, it tends to rotate the shaft 25 in such a direction (counter-clockwise, as viewed in Figure 1, or clockwise, as viewed in Figure 4) as'to move the choke valve I6 toward open position and-to rotate the hollow shaft 24 in such a direction (counter-clockwise, as viewed in Figure 4) as to move the piston 4I away yfrom the head end of the cylinder 38, and (2) as its temperature As shown in Figure 1, when the choke valve I6 is in fully closed position, the center of the pivotal connection between the arm 28 and the link 21 is located slightly to the side of the line joining the axis of the shaft 25 and the center ofthe pivotal connection between the link 21 and the arm 28 opposite that on which it is located when the choke valve is in fully or partially open'position. Consequently, 'when the choke Valve is in fully closed position, now of air through the conduit I I will be ineffective to move the choke valve toward fully openposition and if' the engine be started with the choke valve in this position, it will continue to operate with the choke. valve in fully closed position until the temperature ef the thermo-sensitive element 29 has increased and/or ,the pressure in the intake manifold has decreased to such anextent that the tendency of either orv both of these forces to rotate the shaft 25 in such center after which the iiow of air through the conduit will become a factor in determining the position of the choke valve. The feature of the mechanism described in this paragraph is important because it insures that if the engine on which the mechanism is installed is started when its temperature is lower than `the mentioned predetermined minimum, it will be supplied with the very `rich combustible mixture which is essential to quick and easy starting under these conditions for a sufficiently lengthy period to avoid a false start.

In connection with the mechanism shown in Figures 1, 2, 3 and 4, it will be noted that when the choke valve is in fully closedposition, the pin. 49 on the arm 48 of the bracket 45 is in en. gagement with one arm of the lelement 41 and that the other arm of the element 41 is in engagement with the arm 5| and, consequently, that rotation of the hollow shaft 24| in response to a decrease in the pressure within the intake manifold will be transmitted to the shaft 25 mechanically instead of through the thermo-sensitive element 29, and, therefore, that the considerable force which must be applied to the4 shaft 25 as a result of a decrease in pressure within the intake manifold to move the center of the pivotal connection between the arm 26 and the 1ink 21 over center will not be imposed upon the thermo-sensitive element. In connection with this mechanism, it will also be noted that when kthe throttle valve 52 is moved toward open posifold of an engine similar to that shown in Fig. l

and the reference character 89 a choke valve adjusting mechanism which includes a body 6| which is mounted on and secured to the intake.

manifold.

In the body of the mechanism shown in Figs. 5, 6, 6a, '1 and 8, there is provided a longitudinally extending cylindrical bore 62 which is open at one end and closed at the other by a head 93.` In the .cylindrical bore 92, there is tted a piston 89 which is urged away from the head end/of .the cylinder by a coil spring 61 and'to whose Ahead end there is connected a transversely extending pin 65 whose opposite ends project through longitudinally extending slts 66 in the wall of the cylinder distant from the head end.

The pin 65 and the slots 66 serve both to prevent rotation of the piston in the cylinder and to/ limit the movement of the piston axially of the cylinder in both'directions. y

Into the head of thel cylinder B2 from the upper l side thereof, there extends a transverse bore 68 which terminates short ofthe lower side of the cylinder. The bore 68 is intersected by a bore 69 whichV extends through the' head from the outer to the inner end thereof and by a bore 18 which extends into the head from the inner end thereof versely extending bore 1| which communicates with the interior of the intake manifold I3. The bores 68 and 1| are also interconnected by intersecting bores 12 and 13 which communicate, respectively, with the lower end of the bore 68 and with \an intermediate portion, of the bore 1|. Within the bore 88 whose upper end is closed by a screw plug 14, there islocated e. piston valve 15 which is urged upwardly by the coil spring 16 and in whose cylindrical Wall there are provided two annular grooves 11 and 18.

In upwardly projecting ears 82 which are formed on the body 6|, there is journalled a shaft 19 which extends transversely of the cylinder 62 and projects outwardly beyond the ears. This shaft is connected to the piston. 64 by arms 88 and 88 which arexed to the shaft and links 8| whose opposite ends are pivotally connected, respectively, to the arms 88 and the ends of the pin B5.

On the shaft 19 outwardly of the arm 88, there is journalled a sleeve 84 to whose outer end there is fixed a cup-shaped housing 85 to ywhich is secured the outer end of a bimetallic thermo-sensitive coil spring 8B Whose inner end is fixed to the outer end of the shaft 19. The portion of the shaft 19 between the arm 80 and the inner end of the sleeve 84 extends through an elongated slot 81 in an arm 88 on .which'is formed a rack 89 whose, teeth mesh with those of a pinion 98 which is formed on the adjacent end of the sleeve 84. On the outer end of the arm 88, there is provided a projection 9| which extends into a curved stepped slot 92 which is formed in a plate 93 which is fixed to the body 6|. A screw i8` which extends into the arm 88 through an elongated slo-t H9 in the arm 88 permits the arm-88 to move parallel to the length of the arm 88 but prevents relative rotation of the arms 88 and 88 about the axis of the shaft 19.

On 'the shaft 19, outwardly of the arm B3, there is fixed a sleeve 94 and, outwardly of the sleeve 94, there is. journalled on the shaft 19 an arm 95y on which there is provided a pin 96 which extends into al notch 91 in the sleeve and limits the angle throughout which the arm can rotate with respect to the shaft. The arms 95 and 83 are connectedmby a coil spring 98 which surrounds the sleeveY 94 and whose ends are fixed,

respectively, to the arm 95 and the arm 83. To

.the outer end of the arm 95, there is pivotally connected a link 99 whose outer end is adapted to be connected ,to an arm which is fxedto the shaft of the choke valve of the carburetor of an engine similar to that shown in Figure 1.

, It will be apparent from the drawing that the, mehanism illustrated in Figures 5, 6, 6a, '1, and'8 is adapted to be installed on an engine in the Y. same manner` as the-mechanism illustrated in Figures 1, 2, 3 and 4.

f The thermo-sensitive element 86 isso con-f; structed and arranged that (1) as its tempera' ture rises, it tends to rotate the housing 85 and the sleeve. 84 in such a direction (counter-clockwise, as viewed in Figure 7) that rack and pinion 89"-98 cause the projection 9| on the arm 88 to kthe slot 92 and (3,), .when its temperature falls below a predetermined minimum (e. g., 70 F. to

80 F.) it will maintain the projection 9| in and communicates at its outer end with.l a transabutment with one of the steps 0n the joweredge oi' the slot 92. It will be apparent from the drawing and from what has previously been said that the thermo-sensitive element 86, when its temperature is below the mentioned predetermined minimum, maintains the projection 9| in abutment with one of the steps on the lower edge of the slot 92 and, when its temperature equals or exceeds the mentioned predetermined minimum, v

tends to regulate the position of the projection 9| radially of the slot 92 in accordance with its temperature and, consequently, in accordance with the temperature of the exhaust manifold ||1 and that, functionallyf the thermo-sensitive element 89 differs from .the thermo-sensitive element 29' in that it does not directly affect the position of the choke valve.

It will, however, be noted (assuming that the choke valve is of the type illustrated in Figure 1 and hereinbefore describedythat, when the Lengine on which the mechanism shown in Figures 5, 6, 6a, '7 and 8 is installed is operating, the i'low of air through the air intake conduit of the carburetor and the pressure within the intake manifold of the engine mayaect the position of the choke valve, It is apparent that an increase in the rate of flow of air through the air intake conduit of the carburetor will tend to move the choke valve toward fully open position, increase the tension in the spring 98, and through it rotate the shaft 19 in such a direction as Ito move the piston 64 toward the head end of the cylinder 62 and through the arm 90 and the screw H8 move the projection 9| to the left (as viewed in Figure 1) -ln the slot 92 and that a decrease in the rate of flow of air through the air intake conduit will tend to decrease the tension in the spring 99 and permit the spring 61 to expand and, through the piston 8l, the links 8| and the arms 80 and 83 rotate the shaft 19, in such a direction as to permit the choke valve to move toward fully closed position and, through the mentioned elements and the screw H8, move the projection 9| to the right (as viewed in Figure '1) in the slot 92.

Assuming that the engine on which the chokel va1ve adjusting mechanism shown in Figures 5,

6, 6a, '7 and 8 is installed is operating under such conditions that the pressure within the intake manifold is suflciently low to maintain the piston valve 15 in such a position that the ends of the bore are connected by the groove 18, a decrease in the pressure within the intake manifold will tend to move the piston B4 toward the head end of the cylinder 62 and, through the links 8|, and .the arms 80 and 93, rotate the shaft 19 in such a direction as to decrease the tension in the spring 98 and permit the 'choke valve to move toward fully open position and as, through the mentioned elements and the screw H8, to move the projection 9| to the left (as viewed in Figure '7) in the slot 92 and that an increase in the pressure Within the intake manifold will tend to permit the spring 91 to move 'the piston 'B4 away from the head end of the cylinder '62 and through the elements 8|, 80 and 83 rotate the shaft 19 in such a direction as to increase the tension in the spring 98 and through it move the choke valve toward fully closed positiori and as through the elements 9|, 80, 93 and H8 to move the projection 9| to the right '(as viewed in Figure 7) in the slot 92.

It will be noted that unless 'the pressure within the intake manifold of the engine on which the mechanism illustrated in Figures 5, 6, 6a,- 'I and 8 pendent among other things on the strength of the spring 19, the pressure within the intake manifold will be ineffective in determining the position of the choke valve because While the pressure within the intake manifold is above this value, the cylinder 62 is vented to the atmosphere through the bore 69 and the bore 1| does not communicate with the cylinder 62.

While, as suggested above, normally, the force exerted' on the choke valve by the flow of air through the intake conduit of the carburetor is transmitted to the shaft 19 and the force exerted by the pressure within the intake manifold on the shaft 19 is transmitted to the choke valve through the coil spring 98 which, consequently, functions as a spring load for the choke valve, it will be noted that if these forces exceed a predetermined value, the .pin 96 will engage one end of the notch 9 1 and the forces will be transmitted positively from the shaft 19 to the choke valve and vice versa.

It will be understood from what has heretofore been stated that every change in speed and/or load of, an engine on 'which the mechanism illustrated in Figures 5, 6, 6a, 7 and 8 is installed willl tend to shift the position of the choke valve but that no change in the position of the choke valve beyond limits determined by-the pin 96 and the notch 91 can be effected without moving the projection 91 lengthwise of the slot 92. Consequently, since movement of the projection 9| lengthwise of the slot 92 throughout any considerable distance cannot occur without movement of the projection past one of the steps of the slot, since movement of the projection past one 0f the steps cannot occur unless the radial position of the projection is such that it can move lengthwise of the slot without engaging the radial wall of the step and since the thermo-sensitive element tends to regulate the radial position of the projection in accordance with the temperature of the exhaust manifold of the engine on which the mechanism is installed. the position of the choke valve will be affected by the temperature as well as by the. speed and load of the engine. It will be apparent from what has been pointed out in this paragraph that the mechanism shown in Figures 5, 6, 6a, '1 and 8 may be considered as a choke valve loading spring 98 whose characteristics are variable in accordance with the temperature and speed and load of the engine on which it is installede In the form shown in Figure 9, the choke valve adjusting mechanism includes a base |00 which Y is adapted to be mounted on the intake manifold is secured a cup-shaped housing |06 into which Y the shaft |03 projects and to which is connected the outer end of a bimetallic thermo-sensitive coil spring |01 whose inner end is xed to the. adjacent'end of the shaft I 03. The portion of the shaft |03 between the arms |0| and |02 is partly surrounded by two `hub-like elements |08 and |09, of which the former is flxed' to the shaft, and of which the latter, whichLis connected to the former by a coil spring H8 which surrounds 9 a portion of the shaft |03 and whose ends are fixed, respectively,'to the elements |08 and |09, is rotatably mounted on the shaft |03.

To an arm I I, which is formed on the element |09, there is plvotally connected one end of a piston rod I2 whose opposite end is suitably connected to a .piston i I3 which is located in a cylinder I4 which is formed on the base |00. Within the cylinder H4 there is located a coil spring I|6 which urges the piston upwardly in the cylinder. Through the head of the piston, there extends a passage I I5 which is adapted to be connectedv to the interior of the'intake manifold I3 of the engine on which the choke valve operating mechanism shown in Figure 9 is installed.

It will be apparent from the `drawing that the mechanism illustrated in Figure 9l is adapted 'to be installed on an engine in the same manner as the mechanisms illustrated in Figures 1 to 8.

The thermo-sensitive element |01 is so constructed and arranged-that (1), as its temperature rises, it tends to rotate the shaft |03 in such a direction as to move the choke valve (tolwhich the arm |051 is adapted to be connected in amanner similar to thatin which the arm 26 is connected to the choke valve I6) toward fully open position and as to, through the element |08, the spring I|0, the element |09 and the rod H2, move the piston ||3 toward the head end of the cylinder H0, (2), as its temperature falls, it tends to,

`in the sentence next preceding this, it will be apparent that the thermo-sensitive element |01 functions similarly to the thermo-sensitive eleengine' will tend to move the piston ||3 toward the head end of the cylinder I I4, uncoil the spring ||0 and through it rotate the shaft |03 in such a direction as` to uncoll the thermo-sensitive ele- `ment |01 and move the choke valve toward fully open position and that an increase in the pressure within the intake manifold will tend to permit the spring IIS to expand, move the piston away from the head end of the cylinder, ,coil up the spring I0 and, through it rotate the shaft |03 in such a direction as to coil up the thermo-sensitive. element |01 and move the choke valve toward fully closed position.

While in Figures 5 to 9 the choke valves`which the mechanisms shown therein are designed to operate have not been s hown, and, consequently,

`the connections between the choke :valves 'and sacrifice of efficiency, balanced instead of unbalanced choke valves may be employed in conjunction with the mechanisms herein disclosed and/or throttle position variationactuated elements may ment 29 in that when its temperature is below the mentioned predetermined minimum, it tends to maintain the choke valve in fully closed position and when its temperature equals or exceeds the mentioned predetermined minimum it tends to regulate the position of the choke valve lin accordance with its temperature and, consequently, in accordance with the temperature of the eX- haust manifold ||1.

It will, however, be noted (assuming that the choke valve is of the type illustrated in Figure 1 and hereinbefore described) that, when the engine on which the mechanism shown in Figure 9 is installed is operating, the flow of air through the air intake conduit of the carburetor and the pressure within the intake manifold of the engine, as well as the temperature of the engine affect the position of the choke valve. It is obvious that an increase in the rate of ow of air through the air intake conduit of` the carburetor will tend to move the choke valve toward fully open position and rotate the shaft |03 in such a direction as to uncoil the thermo-sensitive element |01 and the spring I|0 and move the piston piston |I3 away from the head end of the cylbe substituted for the manifold pressure variation actuated elements herein disclosed.

Although I have shown and described preferred embodiments of my invention, it is to be understood that this has been done by way of example and notby way of limitation, and that the scope of my invention is to be determined only by the appended claims.

I claim: l. In a carburetor, an unbalanced choke valve, a thermostat for resiliently closing said valve when cold and opening said valve when hot. a

throttle, means for opening said valve upon opening the throttle wide, and a vacuum motor adapted for operation by manifold vacuum, a lost motion connection between said motor and said valve, permitting a minor movement of said motor without affecting said valve, but opening said valve on extreme movement as upon high vacuum.

2. In an internal combustion engine which in- I cludes a carburetor in which there is Vincorporated a choke valve and a passage which connects the carburetor with a cylinder of the engine, mechsponse to changes in the pressure within the mentioned passage connected to the hollow shaft.

3. In an internal combustion engine which includes a carburetor in which there is incorporated a throttle valve anda choke valve, mechanism for regulating the position of the choke valve which includes a hollow' shaft, a shaft which is connected to the choke valve journalled in the hollow shaft, resilient means interconnecting the specified shafts, means by which the hollow shaft may be rotated, a shaft to which the throttle valve is connected, and elements on the shafts through which motion of the hollow shaft and the third specified shaft may be positively transmitted to the second specified shaft.

, 4. In an internal combustion engine which includes av choke valve which flow of air through It may be well here to mention that, at some,

A 1 the carburetor tends to open, a. throttle valve.

and a passage which connects the carburetorwith a. cylinder of the engine, mechanism for regulating the position of the choke valve which includes means for preventing movement of the choke valve from its closed position by flow of air through the carburetor, a. hollow shaft, a. shaft which is connected to the choke valve journalled in the hollow shaft, a resilient thermostat interconnecting the specliled shafts, a member movable in response to changes in the pressure within the mentioned passage connected to the hollow shaft, a. shaft to which the throttle valve is connested, and elements on the shafts through which motion o! the hollow shaft and the third specied shaft may be positively transmitted to the second speoiiled shaft.

CLARENCE J. SWIGERT.

REFERENCES CITED The following references are of record in the file of this patent: 

